Production of fuel gas by partial oxidation of a hydrocarbonaceous fuel is known in the art. After further processing, the fuel gas is burned in a combustion turbine, purified, optionally mixed with a diluent, such as steam or nitrogen, and burned in a gas turbine to produce mechanical work and electrical energy.
The prior art, however, does not teach or suggest the instant invention. Gasification is integrated with hydrotreating such that hydrogen gas obtained from synthesis gas gasification process is used to hydrotreat petroleum liquids. The remaining synthesis gas is burned in a combustion turbine to generate power. Nitrogen is used to strip hydrogen and volatile hydrocarbons from the hydrotreated petroleum liquid under conditions such that this stripper gas can be sent to the combustion turbine.
The present invention provides an integration of hydrotreating and power generation. The invention comprises using an inert gas, preferably nitrogen, to strip volatiles from a hydrotreated oil. This stripper gas is then added to fuel gas and fed to a combustion turbine, where combustibles in the fuel gas and stripper gas are combusted, and where the exhaust gases are expanded through the turbine to generate power.
In one embodiment, the invention includes an integration of the processes of gasification, hydrotreating, and power generation. The gasification process separates air into substantially pure oxygen and nitrogen. The substantially pure oxygen is used to gasify hydrocarbonaceous material, thereby producing synthesis gas. A hydrogen-enriched gas is separated from the synthesis gas. This hydrogen gas is used to hydrotreat a hydrocarbon liquid, producing an upgraded hydrocarbon liquid but also producing as a byproduct methane, ethane, propane, and the like. The concentration of these hydrocarbons builds up in the hydrogen gas, necessitating a purge stream. This purge stream may be added to the remaining synthesis gas, and this gas is advantageously burned in a combustion turbine to generate power. Nitrogen, a byproduct of the manufacture of substantially pure oxygen, is advantageously added to the combustion turbine fuel to increase power and to reduce nitrous oxides (NOx) emissions. The hydrotreated liquid contains volatile hydrocarbons, hydrogen, and contaminants such as hydrogen sulfide. These volatiles are stripped with the nitrogen byproduct of making the substantially pure oxygen. The stripping is at a pressure sufficient to allow the stripper gas, now containing hydrocarbons and hydrogen, to be added to the combustion turbine fuel without additional compression. This is efficient use of the stripped combustibles, and the nitrogen also increases power generation and reduces NOx emissions.